STMicroelectronics ST25R3918 NFC transceiver

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The ST25R3918 from STMicroelectronics is a multipurpose NFC transceiver supporting passive peer-to-peer functionality and NFC card-emulation mode as well as NFC reader operation. The product enables use cases such as accessory identification for a wide range of applications, including power tools and personal healthcare devices where the device interacts seamlessly with ST25 tags.

Supporting NFC-A and NFC-F card emulation, the unit can be used as an NFC-A/B (ISO 14443A/B) card reader up to high bit rates, as an NFC-V (ISO 15693) reader up to 53 Kbps, as well as ISO 18092 passive initiator and target. The card emulation mode allows support for the newest features available on mobile phones.

End users can use their phones to interact easily with applications that utilise the product, including using a simple tap to start apps on the phone. Device programming and simple NDEF data transfers are also permitted. In addition, users can leverage special stream and transparent modes of the analog front end (AFE) and framing system to implement other custom protocols in card-reader and card-emulation modes.

Combined with the reader mode, the product sports a feature set that allows scanning for tags nearby for tasks such as replaceable detection and parameter setting, or simply reading an access card. Moreover, the user can interact with the mobile phone while collecting valuable data on customer behaviour and accessories used, which adds an additional stream of information for product development.

With high sensitivity and ST’s Noise Suppression Receiver (NSR) technology, the product provides an extended and read range and can be operated with output power around 0.5 W in noisy and harsh environments. It also includes a low-power card-detection mode to scan for the presence of a card by measuring the amplitude or phase of the antenna signal. A low-power RC oscillator and wake-up timer automatically reactivates the device after a selected time period to check for the presence of a tag.

Additional features include support for dynamic power output (DPO), which automatically controls the field strength to meet the required limits. On top of this, active wave shaping (AWS) smooths the waveform for better signal integrity.

The product operates from a wide power-supply voltage range of 2.6–5.5 V between -40 and +85°C, and 2.4–5.5 V in the temperature range from -20 to +85°C, with a peripheral I/O voltage range of 1.65–5.5 V.

For more information: https://www.st.com/st25r3918.